1. Field of the Invention
The present invention relates generally to tennis rackets and more particularly to an improved handle construction.
2. Prior Art
Tennis rackets are constructed of various materials with newer models constructed of graphite, titanium, carbon fiber, Kevlar or other high strength, light-weight materials. The head, neck and handle are typically constructed as a single molded structure. The racket has a stiffness which is substantially predetermined and is a function of the material, racket length and structure.
A goal of racket designers is to provide a "sweet spot" which is as large as possible. The size of the sweet spot is a function of numerous variables including racket stiffness, string tension and others. The larger the sweet spot the more room for error there exists for the player hitting the ball. Providing a racket with a larger sweet spot will improve almost every player's game.
Balls striking the racket face off the longitudinal axis of the racket handle tend to torque or twist the racket in the player's hand causing the struck ball to rebound at an undesirable angle to the direction of motion of the racket and reducing the player's control of the shot. It has been discovered that a racket which provides a torsional elasticity can reduce this deflection angle and improve shots struck off axis.
Injuries to the wrist, elbow or shoulder are sometimes sustained by tennis players from the repeated shocks imparted by striking the ball. Additional injury may result to the wrist from the twisting torque caused by a player striking the ball off the center of the racket face as discussed above. Various designs have been developed to damp the transmission of vibration and shock from the racket to the player. For example, in U.S. Pat. No. 5,236,198 to Haines et al, titled "Games Racket Frame", a discontinuous racket frame is described. The frame has two parts which are joined by a vibration-damping material secured in position by plugs. A reinforcing collar surrounds the discontinuity and together with a rod contained within the vibration-damping material stabilizes the racket handle. This design is intended to reduce the transmission of shock and vibration to the player, thus minimizing the risk of tennis elbow and similar injuries.
Another racket design intended to reduce impact shock is U.S. Pat. No. 5,178,387 to Kuebler titled "Racket for Ball Games, in Particular a Tennis Racket". In this design, a pair of parallel groove-like channels are positioned on opposing sides of the throat and parallel to the racket face to create a hinge. The channels are filled by an elastic shaped mass. However, neither this design nor that of the 5,236,198 patent has found widespread commercial success.
A tennis racket of improved design which reduces or damps some of the shock transmitted to the player would be quite beneficial. Further, a racket which is more flexible or "soft" would provide improved training for an injury-prone player or one recuperating from tennis elbow or other injuries.
The power of the serve with a conventional racket comes from the string tension and the angular velocity of the racket head at the moment the ball is struck. Any design which enhances the energy transferred to the ball by the racket head, even by a small amount, can provide noticeable improvement in a player's serve.
Another important feature of a tennis racket to many tennis players is the feel of the racket when it strikes the ball. This is particularly important for net play when the racket is not so much swung as used to reflect the ball. It has been discovered that the medium frequency components of vibration are the critical part of the feel and should be preserved while the lower and higher frequency components of vibration can be damped.
In most rackets, the weight and balance (feel) are mainly controlled by the handle. For example, the Wilson Classic manufactured by Wilson Racket Sports weighs 345 grams and is a heavy racket designed for strong players. The Wilson 6.2 which weighs 298 grams is a light racket designed for weaker players. In both rackets, the weight of the head, without the handle, is approximately the same. Thus a new design with separate head and handle can continuously vary the total weight and balance (feel) of the racket by adjusting the handle weight.
Recent technology improvements have provided extra long tennis rackets which have been utilized by some top players to improve their games, particularly by increasing the speed of their serves. A racket design which is compatible with different racket lengths is desirable.
It is therefore an object of the invention to provide an improved tennis racket having torsional elasticity and an enlarged sweet spot.
It is a further object of the invention to provide a tennis racket design having vibration damping.
It is another object of the invention to provide a tennis racket with a continuous spectrum of weight and balance.
It is yet another object of the invention to provide an improved tennis racket design having a variable length.